For Internet communications, network nodes always transmit information in packets. The packet format is specified in part by an applicable network-level protocol, and that format includes a network-address field that identifies a node interface to which the packet is directed. A protocol typically used for this purpose is the Internet Protocol (“IP”), which is defined in the Internet Community's Request for comments (“RFC”) 791.
Network Quality of Service (QoS) mechanisms focus on how to guarantee bandwidth between a given known pair of nodes. Examples of such mechanisms are int-serv, (including RSVP) and diff-serv.
Providing end-to-end QoS guarantees for content delivery across the internet presents a number of challenges for service providers, including, the ability of network mechanisms to support QoS. This is because QoS support is not widely available. It is therefore hard or almost impossible at present to provide QoS guarantees across multiple networks as there are no agreed standard mechanism and service level agreement (SLA) guarantees in place. In addition there is presently no single accepted scheme to support QoS guarantees for internet protocol based (IP-based) applications, although RSVP is the prevailing standard for network resource reservation. Consequently, different QoS mechanisms are needed for different access technologies.
Typically load balancing algorithms are used for picking the best server in a network, with respect to server capacity, for satisfying a request. However they can not guarantee QoS for the whole duration of the network transaction, i.e. they can not guarantee network connectivity or capacity throughout the whole of the session.
Load re-balancing refers to the ability of a client enabled with processes in accordance with a specified network mechanism, to re-map a path through a plurality of nodes to a resource. Modern requirements demand that any load balancing system be scalable. Such scalability limits the degradation of system response time as new members, nodes or objects are added, removed or modified within the existing infrastructure.
In ATM networks, the ATM “Anycast” mechanism is employed to overcome this problem, however in the IP domain the Anycast mechanism does not provide a QoS guarantee. Also, in the IP domain, the Anycast mechanism does not take server load capability into account, instead only the network speed is taken into consideration when selecting the best path.
It is a general objective of the present invention to overcome or significantly mitigate one or more of the aforementioned problems.